Electrodiagnostic significance of supramaximally stimulated A-waves

Muscle & Nerve
J Rowin, M N Meriggioli

Abstract

A-waves are generally considered a nonspecific finding of unclear electrodiagnostic and clinical significance. We systematically identified A-waves during routine F-wave studies and defined them as supramaximally elicited reproducible intermediate to late responses that are clearly separate from the M-responses. In patients with A-waves, we noted electrophysiologic diagnoses, the nerve in which the A-wave was identified, the presence of A-waves in multiple nerves, and A-wave morphology. In 54 of 1,258 studies performed, A-waves were present in one or more nerves. Electrophysiologic diagnoses in patients with A-waves included diffuse axonal neuropathy (11.5%), demyelinating neuropathy (66.7%), motor neuron disease (6.5%), radiculopathy (3.6%), mononeuropathy (3.9%), and normal (tibial nerve only) 0.7%. A-waves were abnormal when found in any nerve except the tibial nerve. They were particularly prevalent and present in multiple nerves in acquired and hereditary demyelinating neuropathies, and they more often had a complex morphology. We postulate that demyelination is the crucial underlying pathophysiologic correlate of the supramaximally stimulated A-wave.

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Citations

Jun 19, 2010·Neurological Sciences : Official Journal of the Italian Neurological Society and of the Italian Society of Clinical Neurophysiology·Ferdinando SartucciAlessandro Rossi
May 8, 2004·Neurophysiologie clinique = Clinical neurophysiology·S BoukhrisJean-Michel Vallat
Mar 18, 2008·Clinical Toxicology : the Official Journal of the American Academy of Clinical Toxicology and European Association of Poisons Centres and Clinical Toxicologists·Bart F WerbrouckJan L De Bleecker
Oct 23, 2003·Muscle & Nerve·Leena PuksaBjörn Falck
Nov 8, 2011·Clinical Neurophysiology : Official Journal of the International Federation of Clinical Neurophysiology·Shingo KawakamiTeruo Shimizu
Jan 11, 2005·Neurophysiologie clinique = Clinical neurophysiology·F Mesrati, M F Vecchierini
May 31, 2018·Journal of Clinical Neurophysiology : Official Publication of the American Electroencephalographic Society·Sindhuja LakshminarasimhanLakshminarasimhan Ranganathan
Sep 25, 2018·Journal of Clinical Neurophysiology : Official Publication of the American Electroencephalographic Society·Liborio RampelloAntonio Arcidiacono
Aug 23, 2017·Brain and Behavior·Iva SrotovaJosef Bednarik

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